1. Field of the Invention
The present invention is directed to a system for attaching a rigid object to a deformable model and, more particularly, to a system that uses the average deformation to position the object on the model.
2. Description of the Related Art
The present invention provides an efficient way to attach rigid objects, or rigid areas to deformed or deformable shapes. Several types of deformations have been proposed in the last decade. Cartoon like non-linear deformations use linear transformation with variable coefficients. Free Form Deformations and their extensions are volumetric spline based. Axis or curve based deformations have also been introduced. All these methods ultimately define a deformation field from R3 to R3 that will be used as input for the algorithm of the present invention.
Physically based deformations models and more specifically cloth deformations work on sampled solids or surfaces. The deformation is only known at some specific vertex position.
So far, most articles dealing with rigid object animation use a physically based model. The user defines forces and behavior, then some engine computes the animation. While this method is suited for complex realistic motion, it is hard for artists to control the result, or break the physical realism to give more emotion to the animation. This situation happens often in the animation process, and no tool is currently available to easily solve this problem.
What is needed is a direct approach, where users will benefit from the wide range of existing deformation tools, while adding minimal interaction or computation overhead, to determine the animation of the rigid parts.
It is an object of the present invention to provide an efficient way to attach rigid objects, or rigid areas to deformed shapes.
It is also an object of the present invention to allow rigid objects to be animated with deforming shapes.
It is an additional object of the present invention to allow animation of rigid objects by having them fly into a three-dimensional deforming field, such as modeling wind using a procedural model and using the average local air deformation to compute the rigid object position and orientation.
The above objects can be attained by a system that produces a position and an orientation of a rigid object connected to a deformed two or three-dimensional model at each cycle in an animation by performing isotropic removal of shear and scaling from a linear transformation of an average deformation of the model. A volumetric area of the deformed model which is used for the position determination is specified. The average deformation of the area is calculated and the linear transformation of the object is performed with the average deformation.
These together with other objects and advantages which will be subsequently apparent, reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.